1 | // -*- C++ -*- |
2 | //===----------------------------------------------------------------------===// |
3 | // |
4 | // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. |
5 | // See https://llvm.org/LICENSE.txt for license information. |
6 | // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception |
7 | // |
8 | //===----------------------------------------------------------------------===// |
9 | |
10 | #ifndef _LIBCPP___SSO_ALLOCATOR |
11 | #define _LIBCPP___SSO_ALLOCATOR |
12 | |
13 | #include <__config> |
14 | #include <type_traits> |
15 | #include <new> |
16 | |
17 | #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) |
18 | #pragma GCC system_header |
19 | #endif |
20 | |
21 | _LIBCPP_BEGIN_NAMESPACE_STD |
22 | |
23 | template <class _Tp, size_t _Np> class _LIBCPP_HIDDEN __sso_allocator; |
24 | |
25 | template <size_t _Np> |
26 | class _LIBCPP_HIDDEN __sso_allocator<void, _Np> |
27 | { |
28 | public: |
29 | typedef const void* const_pointer; |
30 | typedef void value_type; |
31 | }; |
32 | |
33 | template <class _Tp, size_t _Np> |
34 | class _LIBCPP_HIDDEN __sso_allocator |
35 | { |
36 | typename aligned_storage<sizeof(_Tp) * _Np>::type buf_; |
37 | bool __allocated_; |
38 | public: |
39 | typedef size_t size_type; |
40 | typedef _Tp* pointer; |
41 | typedef _Tp value_type; |
42 | |
43 | _LIBCPP_INLINE_VISIBILITY __sso_allocator() throw() : __allocated_(false) {} |
44 | _LIBCPP_INLINE_VISIBILITY __sso_allocator(const __sso_allocator&) throw() : __allocated_(false) {} |
45 | template <class _Up> _LIBCPP_INLINE_VISIBILITY __sso_allocator(const __sso_allocator<_Up, _Np>&) throw() |
46 | : __allocated_(false) {} |
47 | private: |
48 | __sso_allocator& operator=(const __sso_allocator&); |
49 | public: |
50 | _LIBCPP_INLINE_VISIBILITY pointer allocate(size_type __n, typename __sso_allocator<void, _Np>::const_pointer = 0) |
51 | { |
52 | if (!__allocated_ && __n <= _Np) |
53 | { |
54 | __allocated_ = true; |
55 | return (pointer)&buf_; |
56 | } |
57 | return static_cast<pointer>(_VSTD::__libcpp_allocate(__n * sizeof(_Tp), _LIBCPP_ALIGNOF(_Tp))); |
58 | } |
59 | _LIBCPP_INLINE_VISIBILITY void deallocate(pointer __p, size_type __n) |
60 | { |
61 | if (__p == (pointer)&buf_) |
62 | __allocated_ = false; |
63 | else |
64 | _VSTD::__libcpp_deallocate(__p, __n * sizeof(_Tp), _LIBCPP_ALIGNOF(_Tp)); |
65 | } |
66 | _LIBCPP_INLINE_VISIBILITY size_type max_size() const throw() {return size_type(~0) / sizeof(_Tp);} |
67 | |
68 | _LIBCPP_INLINE_VISIBILITY |
69 | bool operator==(__sso_allocator& __a) const {return &buf_ == &__a.buf_;} |
70 | _LIBCPP_INLINE_VISIBILITY |
71 | bool operator!=(__sso_allocator& __a) const {return &buf_ != &__a.buf_;} |
72 | }; |
73 | |
74 | _LIBCPP_END_NAMESPACE_STD |
75 | |
76 | #endif // _LIBCPP___SSO_ALLOCATOR |
77 | |